Scientific Intelligence. 
Distance in 
toises. 
Time in which 
Sound moved 
through it. 
Velocity of Sound 
per second, 
Toises. Metres, 
Barom. 
Therm. 
centig. 
43,365 
38"0 
190.2 or 270.7 1 
21°3 
50,316 
43.3 
193.6 
Metre. 
- 0.697 
25.0 
29,558 
26.0 
189.5 
369.3 
25.0 
13,841 
12.2 
189.1 
368.6 
22.5 
The mean of these results is 190.6 toises or 371.5 metres, or 
1219 English feet, at a temperature of 23°. 5 ; or if we take the 
two hrst observations, which were made at the greatest distan- 
ces, we shall have 191.9 toises or 374^ metres, or 1227 Enghsh 
feet, at the temperature of 23° of the centigrade thermometer. 
14. Poissoils Reseai'clies on Wind Instrument s,-^ A. yevy 
and interesting memoir on the theory of wind instruments, by 
that eminent mathematician M. Poisson, was read at the Institute 
on the 8th February 1819. An abstract of it is published in 
the Ann. de Chim. e.t dc Phys. for Feb. 1819. 
II YD ROD YX A M I C S . 
15. Compression of Water. — The compressibility of water, 
which ^\^as long ago established by Mr Canton, and also by M. 
Zimmerman, has been recently examined by Professor (Ersted. 
He has found, contrary to the opinion of Zimmerman, that the 
compression of water is proportional to the compressing forces, 
as Canton had affirmed on the evidence of a few experiments ; 
and that the actual compression is always three times greater 
than that v/hich was found by Canton. In confirmation of his 
own results, M. (Ersted has shewn that the velocity of sound 
in water, as given by M. La Place, may be calculated from them. 
At 14° of Reaumur, he considers the compression of water as 
equal to about the 0.00013, or the thirteen hundred thousandth 
part of its bulk. 
16. New retaining Syphon> — A new syphon which has the 
great advantage of retaining its charge, has been suggested, and 
used, by Mr Hunter of Thurston. It is shewn in Plate II. Fig, 
3. where A, B, are two small cups fixed to the ends of the un- 
equal branches, by two arms C C. When it is charged in the 
usual way, and has been in use, it will stand vertically upon 
the boxes A, B, as a base, so that when it is lifted by the ring 
P, it may be replaced, and will act as formerly. The same 
